Of course they are not. But they don't destroy music enough to commit suicide "when used appropriately" ;-)
Like-you, i try to avoid them as much as i can.
Sometimes here, try to express nuanced opinions is a wireline dancer work.
It seems to me that using a servo is better than adding an electrolytic cap to a feedback network in order to remove any output offset, as we once did decades ago, so I agree with both Bob Cordell and Esperado on this, for the reasons that they have already made. I even use coupling caps when necessary, however, I find that I can fairly easily design out most coupling and feedback caps without adding to the cost in any significant way. It improves reliability, because electrolytic caps are not the most reliable component, especially the 'cost effective ones'. Is there a sonic difference between audio quality and the cheapest electrolytic caps? Probably, but I cannot prove it to everyone's satisfaction. I do know that the audio caps usually use copper rather than steel leads.
That may be important.
That may be important.
Keantoken,
To answer your question about price my goal is to keep this under $1,500 max and hopefully much less if possible. At this time I have no idea what it is going to cost to have a nice amplifier and xo, with as many surface mount devices as possible for size reduction stuffed and assembled. I am zeroing in on the final design of what I want to use and will have to shop the actual assembly and board production and see what that is going to cost, I have no experience in pricing that so can't make any definitive estimation of cost for that part of the speaker. The speaker side of things I have a pretty good handle on, the enclosures themselves will not be cheap to make as I am going to be using a high dollar material to produce those enclosures but that is something that I did professionally for years myself. I make the cones myself so I understand that and I actually made and assembled the original prototype cone drivers and have designed the tweeter also. I have to look at the difference in cost between domestic electric steel vs foreign made electric steel, the American manufacturer is quite expensive and really doesn't want to even talk to speaker builders as they want to sell by the ton the material. That material also requires annealing after machining or forming so that is another cost. I have done the analysis and I may be able to use 1008 steel for the cup of the motor assembly but it would be a mistake to use that type of low carbon steel for the pole pieces, it would go into saturation. I know we keep hearing that American manufacturers are now competing with Asian sources on price but that is so far from the truth it isn't funny. I have to deal with this on other projects that are not audio related, there is a real disconnect going on when I hear those words. I will be getting the tooling quotations soon to produce the molds off shore, I know what they would cost in the USA, I have quoted that sort of thing for years and there is an astronomical difference between domestic and Asian sources. You just have to know how to specify and qualify the quality level that you demand, that is much of the secret to working off shore. Stay tune though, this is going to happen.
To answer your question about price my goal is to keep this under $1,500 max and hopefully much less if possible. At this time I have no idea what it is going to cost to have a nice amplifier and xo, with as many surface mount devices as possible for size reduction stuffed and assembled. I am zeroing in on the final design of what I want to use and will have to shop the actual assembly and board production and see what that is going to cost, I have no experience in pricing that so can't make any definitive estimation of cost for that part of the speaker. The speaker side of things I have a pretty good handle on, the enclosures themselves will not be cheap to make as I am going to be using a high dollar material to produce those enclosures but that is something that I did professionally for years myself. I make the cones myself so I understand that and I actually made and assembled the original prototype cone drivers and have designed the tweeter also. I have to look at the difference in cost between domestic electric steel vs foreign made electric steel, the American manufacturer is quite expensive and really doesn't want to even talk to speaker builders as they want to sell by the ton the material. That material also requires annealing after machining or forming so that is another cost. I have done the analysis and I may be able to use 1008 steel for the cup of the motor assembly but it would be a mistake to use that type of low carbon steel for the pole pieces, it would go into saturation. I know we keep hearing that American manufacturers are now competing with Asian sources on price but that is so far from the truth it isn't funny. I have to deal with this on other projects that are not audio related, there is a real disconnect going on when I hear those words. I will be getting the tooling quotations soon to produce the molds off shore, I know what they would cost in the USA, I have quoted that sort of thing for years and there is an astronomical difference between domestic and Asian sources. You just have to know how to specify and qualify the quality level that you demand, that is much of the secret to working off shore. Stay tune though, this is going to happen.
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If you have reached your favourable flux value, then pole piece saturation is not a bad thing (you don’t risk flux modulation anymore)
My warmest wishes for your successful endeavor.
George
Reliability of electrolytic capacitors:
If you look up the repair statistics..... the most frequent part to fail is the electrolytic cap.
Consumer electronic like receivers, cd players etc use caps with life time of typically 1000 to 2000 Hours. They do not necessarily fail outright at 1000 hours but will no longer meet mfr specs. Esp the loss tang. You can figure your own situation on how long 1000hr will be in play or ON time at your house. The better caps will last 5000-10,000 hours at rated load before performance has deteriorated by the specified amount. These are typically the ones also rated at 105C or higher. BUt cost more, of course. The dc servo will last almost forever without any deterioration over time. And are very reliable. And will cost less than a 105C electro.... If the circuit uses low Z values for noise and speed etc.... the C value will be larger and costly for high performance and long life... as well as physically large.
THx-RNMarsh
If you look up the repair statistics..... the most frequent part to fail is the electrolytic cap.
Consumer electronic like receivers, cd players etc use caps with life time of typically 1000 to 2000 Hours. They do not necessarily fail outright at 1000 hours but will no longer meet mfr specs. Esp the loss tang. You can figure your own situation on how long 1000hr will be in play or ON time at your house. The better caps will last 5000-10,000 hours at rated load before performance has deteriorated by the specified amount. These are typically the ones also rated at 105C or higher. BUt cost more, of course. The dc servo will last almost forever without any deterioration over time. And are very reliable. And will cost less than a 105C electro.... If the circuit uses low Z values for noise and speed etc.... the C value will be larger and costly for high performance and long life... as well as physically large.
THx-RNMarsh
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And another alternative
When I was enlisted to come up with a "blameless" switching system for Harman R&D, and when the budget was unlimited (a bit like American Express, no preset spending limits
), I had a big pile of Toshiba JFETs, the 2SK364BL, which although specified for analog switching have the same die as the good-sized 2SK170. Oddly I didn't notice the dual 2SK389 at the time.
I had a test jig that brought the devices under test to a constant temperature. A tech sorted through the lot after a pre-screen for minimum Idss. The parts were then binned for both Vth and Idss, and the two-parameter data was used to select matched pairs. They were then mounted in aluminum blocks with a temp sensor and heater, the notion being that they'd be operated at a regulated temperature slightly above ambient. These were to form the first stage of some discrete line-level balanced amplifiers, prefacing a switched resistor array for level matching which was then followed by buffer amplifiers.
By the time I got close to this realization, the money that was unlimited became a good deal more constrained, and I wound up dialing down the ambitious design for a less costly alternative. I have a bunch of the aluminum-mounted pairs to this day, I think at least 32 to cover an 8 channel balanced system.
But the notion was to have sufficiently low offset voltage and drift to preclude the need for d.c. blocking or servos. This was fairly easy too as the required gains were not large. Of course this supposed no offset in the sources.
Despite an AES preprint from 1997 describing the simpler system, the money to complete it dried up completely, and I have no idea what they are using for line-level switching and level matching now. I am almost afraid to ask in fact
Brad
When I was enlisted to come up with a "blameless" switching system for Harman R&D, and when the budget was unlimited (a bit like American Express, no preset spending limits
), I had a big pile of Toshiba JFETs, the 2SK364BL, which although specified for analog switching have the same die as the good-sized 2SK170. Oddly I didn't notice the dual 2SK389 at the time.I had a test jig that brought the devices under test to a constant temperature. A tech sorted through the lot after a pre-screen for minimum Idss. The parts were then binned for both Vth and Idss, and the two-parameter data was used to select matched pairs. They were then mounted in aluminum blocks with a temp sensor and heater, the notion being that they'd be operated at a regulated temperature slightly above ambient. These were to form the first stage of some discrete line-level balanced amplifiers, prefacing a switched resistor array for level matching which was then followed by buffer amplifiers.
By the time I got close to this realization, the money that was unlimited became a good deal more constrained, and I wound up dialing down the ambitious design for a less costly alternative. I have a bunch of the aluminum-mounted pairs to this day, I think at least 32 to cover an 8 channel balanced system.
But the notion was to have sufficiently low offset voltage and drift to preclude the need for d.c. blocking or servos. This was fairly easy too as the required gains were not large. Of course this supposed no offset in the sources.
Despite an AES preprint from 1997 describing the simpler system, the money to complete it dried up completely, and I have no idea what they are using for line-level switching and level matching now. I am almost afraid to ask in fact
Brad
When saturation starts to occur, the field lines will start to go through the air.
I suspect that that is indeed a bad thing. It causes an asymmetrical inductance, kind of a flux rectification as it were.
jn
Darn Bcarso, you went all out! At the time, there was also the NPD5564 and the 2SK240 available, years before the 2SK389. They all worked pretty well. The NPD5564 was a monolithic matched fet pair from National, and the 2SK240 was two 2SK170's that were computer matched and factory placed inside an aluminum can.
Some people hold out for full DC operation, and I cannot disagree with them, except for the hassle. Servos are easy, BUT can be problematic if compromised in some serious way. Usually it has to do with using the servo as an audio filter, as well as a DC control, or not decoupling the servo well enough.
Some people hold out for full DC operation, and I cannot disagree with them, except for the hassle. Servos are easy, BUT can be problematic if compromised in some serious way. Usually it has to do with using the servo as an audio filter, as well as a DC control, or not decoupling the servo well enough.
It would be interesting to examine. Of course A/B is a lot simpler than A/B/C.... with computer control of randomized selections and preset level matching, with as well a fadeup and fadedown, and masking noise to conceal cues about the pneumatic loudspeaker mover.
At one point the objective was to test anything: sources, preamps, power amps, and of course loudspeakers. Even cables I suppose
But I think all that was done was loudspeakers.
jneutron,
That is some of what I would see when the pole piece would saturate, strange flux leakage looking for a way back around. I tried my damnedest to avoid any leakage paths, in one design I tried so hard to increase flux density by ever increasing the magnetic mass and surface area and no matter what I did I could not increase the effective energy in the gap, I gave up in that idea.
On another subject. I have not forgotten about the clock, I've just been really busy trying to finish a design for a project not audio related, It has been a real bear as the design goals kept changing until they had me design myself into a corner and then the device couldn't work like intended due to the visual look they wanted, they lost the fact of what we were attempting to do in the first place and I have had to design my way out of that quandary. I had to learn about light and lenses, something I never had to consider before. I'll email you some pics once my daughter comes back from vacation with the digital camera that will pick up the details of the clock inner workings. .
That is some of what I would see when the pole piece would saturate, strange flux leakage looking for a way back around. I tried my damnedest to avoid any leakage paths, in one design I tried so hard to increase flux density by ever increasing the magnetic mass and surface area and no matter what I did I could not increase the effective energy in the gap, I gave up in that idea.
On another subject. I have not forgotten about the clock, I've just been really busy trying to finish a design for a project not audio related, It has been a real bear as the design goals kept changing until they had me design myself into a corner and then the device couldn't work like intended due to the visual look they wanted, they lost the fact of what we were attempting to do in the first place and I have had to design my way out of that quandary. I had to learn about light and lenses, something I never had to consider before. I'll email you some pics once my daughter comes back from vacation with the digital camera that will pick up the details of the clock inner workings. .
Sorry I was unclear. This was a consumer product. I think it had 4 selectable inputs as well as volume and balance.
edit: found it, it was called the SRC.
http://www.canuckaudiomart.com/deta...earch_ar_stereo_remote_control_src_component/
Yah, once you get over 2 or 3 tesla, the iron pretty much gives up. There are interesting rare earth alloys that can hold the flux into the 4 and 5 tesla range (IIRC, vanadium was involved), but they are expensive even for what we do. We tend to add iron to the outside of our magnets until the flux leakage is down to a respectable level, unlike the robot sucking field depicted in terminator 3. (even though she gets pulled up against a feature we call the interconnect region...where we solder the joints between magnets). No fields there.
Sure no problem. I've also had a few issues to contend with at home as well.
Life is what happens while you're making plans...
jn
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Yes, the servo should not be used for setting some infrasonic cutoff, such as attendant on vinyl playback with warpage and tonearm/cartridge resonances. And some will not control nearly-coincident pole-pairs in the system and have horrendous ringing. It seems the late Jim Bongiorno had some difficulties in this regard, according to Dan Siefert, who worked for GAS at the time.
It's a little tricky. I recall Keith Johnson mentioning somewhere that people were doing servos wrong, probably in connection with his contributions to some Spectral gear, but I never got the details.
Brad
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